Dumb Terminal Keyboard

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Dumb Terminal Keyboard

So I have this old keyboard from a dumb terminal which I think would be perfect for my vision of an Apple I.  I would  also kind of like to convert it USB just for grins.  I don't know anything about it other than what is in the pics below.   While I wrote a lot of code on these things in college, that is the limit of my experience with them.  I'm guessing it could be an ASCII keyboard using a serial connection through the RJ-11.  It could also be some smarts were in the rest of the terminal. So here are my initial guesses and how to begin figuring out how this thing works.

 

If it is a serial ASCII keyboard (perfect for an Apple I) then I would guess it communicates at 9600,8.1.none, none or 9600,7,1,none,none.  I could connect it up to a serial port and accept input using terminal software after adapting the connectors.  I would guess green is frame gound, black is signal ground and red and yellow are TX or RX.  Is that likely? Is my testing plan reasonable? If that is true how would I adapt it for an Apple I reproduction board? I might keep the keyboard in the original case and mount a RJ-11 jack in my Apple I case.

 

If it is serial then I could  also adapt it using a Raspberry Pi or some arduino to USB.   I think some Pi GPIO/UART solution could be fairly straight forward. Does anybody know of premade solutions for this I could start with to jump start my plan.

 

Otherwise I start to map and decode the switch map using GPIOs on a Pi.  Both of those likely take more time than I will have for a while so if anybody has experience with existing solutions, I'd love suggestions which are closer to "plug it into this thing and then connect the USB"

 

 

 

 

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The 8048 microcontroller

The 8048 microcontroller could be doing any kind of enoding including serial ASCII, row-column or per-key pulse encoding, or a key-code encoding scheme.  What terminal did this come from?

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Source unknown

I have no idea what terminal it came from.  I had it in a box of "junk".  So should I start with serial ASCII per my earlier idea? If it is not serial ASCII what would be your next steps? I assume row-column would be integer pairs indicating 0,0 or 1,1 as ESC??  I'm guessing it must be some type of serial with just 3 wires out to the RJ-11.

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